Testing interposer method and apparatus

ABSTRACT

The disclosure describes a novel method and apparatus for improving silicon interposers to include test circuitry for testing stacked die mounted on the interposer. The improvement allows for the stacked die to be selectively tested by an external tester or by the test circuitry included in the interposer.

FIELD OF THE DISCLOSURE

This application is a divisional of prior Application No. 17/147,638,filed Jan. 13, 2021, currently pending and scheduled to grant as U.S.Pat. No. 11,644,482;

Which was a divisional of prior Application No. 16/747,055, filed Jan.20, 2020, now U.S. Pat. No. 10,928,419, issued Feb. 23, 2021;

Which was a divisional of prior Application No. 16/247,134, filed Jan.14, 2019, now U.S. Pat. No. 10,591,510 issued Mar. 17, 2020;

Which was a divisional of prior Application No. 15/590,199, filed May 9,2017, now U.S. Pat. No. 10,215,774, issued Feb. 26, 2019;

Which was a divisional of prior Application No. 14/826,617, filed Aug.14, 2015, now U.S. Pat. No. 9,671,426, issued Jun. 6, 2017;

Which was a divisional of prior Application No. 14/635,656, filed Mar.2, 2015, now U.S. Pat. No. 9,146,276, issued Sep. 29, 2015;

Which was a divisional of prior Application No. 13/495,451, filed Jun.13, 2012, now abandoned;

Which claims priority from Provisional Application No. 61/498,714, filedJun. 20, 2011. All of which are hereby incorporated by reference intheir entirety.

This disclosure relates generally to silicon interposers andspecifically to silicon interposers that, according to the disclosure,include embedded test circuitry.

BACKGROUND OF THE DISCLOSURE

Integrated circuit die may be designed such that they may be stacked ontop of one another to form a stacked die arrangement. The stacked diearrangement may be further mounted upon a silicon interposer layer/die.The silicon interposer serves as a signal redistribution layer forconnecting the fine pitch contact points of the stacked die to widerpitch contact points of a substrate, such as, but not limited too, aboard. Prior to mounting onto a substrate the stacked die and interposerensemble must be tested to assure goodness. Testing is done byconnecting a tester to the interposer and applying test patterns to thestacked die via the interposer.

FIG. 1 illustrates a device 100 including a stack of die 102-104 mountedupon a conventional silicon interposer 106. The interposer 106 isfurther mounted to a substrate 108, such as, but not limited too, asmart phone printed circuit board (PCB), a desk top computer PCB, a laptop computer PCB, a tablet PCB or another die. The die 102-104 in thisexample are designed using Through Silicon Vias (TSV) 110. TSVs areconnectivity paths formed between the top and bottom surfaces of thedie. TSVs allow substrate input 118 and output 120 signals to flowvertically up and down the die stack via the interposer to provide inputto and output from the die circuitry 112 of each die. The die 102-104are locally connected together via connections 114. The signalconnections between die 102 and 104, between die 104 and interposer 106and between interposer 106 and substrate 108 are indicated by contactpoints 116.

FIG. 2 is provided to illustrate the redistribution layer function ofthe interposer 106 to spread connections from fine pitch contact points116 of die 104 to wider pitch contact points 116 of the substrate 108.

FIG. 3 is a schematic representation of the die stack and interposer ofFIG. 1 that will be used to facilitate the description of thedisclosure. For simplicity, the local die connections 114 are not shownin FIG. 3 .

FIG. 4 illustrates die circuitry 112 which includes functional circuitry402 for performing the functional operation of the die and embedded testcircuitry 404 for testing the functional circuitry. The inputs 118 andoutputs 120 of the die circuitry 112 are coupled to the functional 402and test circuitry 404. During functional operations the functionalcircuitry operates by inputting functional signals from inputs 118 andoutputting functional signals to outputs 120. During test operations thetest circuitry operates by inputting test stimulus and test controlsignals from some or all of the inputs 118 and outputting test responsesignals to some or all of the outputs 120.

FIG. 5 illustrates a tester 502 connected to the interposer 106 to inputstimulus (S) and control (C) signals to the test circuitry 404 of die102 and 104 and to receive response (R) signals from the test circuitry404 of die 102 and 104. The stimulus and control signals are input fromthe tester using some or all of the inputs 118 and the response signalsare output to the tester using some or all of the outputs 120.

The following disclosure describes a new method of controlling the testcircuitry 404 of die 102 and 104. The new method is achieved byembedding die test and access circuitry within the interposer 106.

BRIEF SUMMARY OF THE DISCLOSURE

This disclosure describes an interposer that is improved to includetesting circuitry and IEEE 1149.1 Test Access Port (TAP) circuitry. Theimproved test interposer can be used in place of conventionalinterposers 106 to facilitate the testing of a die or a stack of diemounted thereupon.

BRIEF DESCRIPTIONS OF THE VIEWS OF THE DRAWINGS

FIG. 1 illustrates stacked die on an interposer mounted on a substrate.

FIG. 2 illustrates the input and output signal redistribution functionof the interposer.

FIG. 3 illustrates an alternate view of FIG. 1 .

FIG. 4 illustrates functional and test circuitry in a die.

FIG. 5 illustrates stacked die on an interposer connected to a tester.

FIG. 6 illustrates stacked die on a test interposer connected to atester, according to the disclosure.

FIG. 7 illustrates an alternate view of FIG. 6 .

FIG. 8 illustrates a first view of the test interposer of thedisclosure.

FIG. 9 illustrates a second view of the test interposer of thedisclosure.

FIG. 10 illustrates the TAP of the test interposer.

FIG. 11 illustrates the TAP state diagram.

FIG. 12 illustrates a test interposer coupled to a test compressioncircuit of a die.

FIG. 13 illustrates the test compression circuit.

FIG. 14 illustrates the TAP controlling stimulus and response circuitryin the test interposer of FIG. 12 .

FIGS. 15-16 illustrate stimulus generator circuits of the disclosure.

FIGS. 17-20 illustrate N to M conversion circuits of the disclosure.

FIGS. 21-22 illustrate response collector circuits of the disclosure.

FIGS. 23-24 illustrate M to N conversion circuits of the disclosure.

FIG. 25 illustrates a response collector circuit of the disclosure.

FIG. 26 illustrates a response compare circuit of the disclosure.

FIG. 27 illustrates a pass/fail response comparator.

FIG. 28 illustrates a response collector circuit of the disclosure.

FIG. 29 illustrates a test compression circuit being tested by the testinterposer.

FIG. 30 illustrate the TAP state transitions during the test of FIG. 29.

FIG. 31 illustrates a test compression circuit being tested by the testinterposer and a tester.

FIG. 32 illustrates the TAP state transitions during the test of FIG. 31.

FIG. 33 illustrates a test interposer coupled to a test compressioncircuit of a die.

FIG. 34 illustrates the TAP controlling stimulus, control and responsecircuitry in the test interposer of FIG. 33 .

FIGS. 35-36 illustrate stimulus generator circuits of the disclosure.

FIGS. 37-40 illustrate response collector circuits of the disclosure.

FIG. 41 illustrates a test compression circuit being tested by the testinterposer.

FIG. 42 illustrate the TAP state transitions during the test of FIG. 41.

FIG. 43 illustrates a testable memory being tested by the testinterposer.

FIG. 44 illustrates a testable memory.

FIG. 45 illustrates the TAP controlling stimulus, control and responsecircuitry of the testable memory of FIG. 43 .

FIG. 46 illustrates a testable memory being tested by the testinterposer.

FIG. 47 illustrate the TAP state transitions during the test of FIG. 43.

FIG. 48 illustrates a testable ADC being tested by the test interposer.

FIG. 49 illustrates a testable ADC.

FIG. 50 illustrates the TAP controlling stimulus, control and responsecircuitry of the testable ADC of FIG. 48 .

FIGS. 51-53 illustrate stimulus generator circuits of the disclosure.

FIG. 54 illustrates a testable ADC being tested by the test interposer.

FIG. 55 illustrates the TAP state transitions during the test of FIG. 54.

FIG. 56 illustrates a testable DAC being tested by the test interposer.

FIG. 57 illustrates a testable DAC.

FIG. 58 illustrates the TAP controlling stimulus, control and responsecircuitry of the testable DAC of FIG. 56 .

FIG. 59 illustrates a response collector circuit of the disclosure.

FIG. 60 illustrates a testable DAC being tested by the test interposer.

FIG. 61 illustrates the TAP state transitions during the test of FIG. 60.

FIG. 62 illustrates stacked die mounted upon a first example realizationof the test interposer of the disclosure, which is based upon separatebussing of stimulus, control and response signals.

FIG. 63 illustrates stacked die mounted upon a second examplerealization of the test interposer of the disclosure, which is basedupon common bussing of stimulus, control and response signals.

FIG. 64 illustrates an example of a programmable stimulus generator,according to the disclosure.

FIG. 65 illustrates an example of a programmable control generator,according to the disclosure.

FIG. 66 illustrates an example of a programmable response collector,according to the disclosure.

FIG. 67 illustrates an example of where the test interposer of thedisclosure is incorporated into the bottom die of a stack of die,eliminating the need for a separate test interposer layer in the stackeddie arrangement.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 6 illustrates the die stack of FIG. 3 with the conventionalinterposer 106 being replaced with the test interposer 602 of thepresent disclosure. The test interposer 602 is similar to theconventional interposer 106 of FIG. 3 in that in functional mode it canpass functional inputs 118 from a substrate 608 to the functionalcircuitry of die circuitry 112 and pass functional outputs 120 from thefunctional circuitry of die circuitry 112 to the substrate 608.

FIG. 7 illustrates the die stack of FIG. 5 with the conventionalinterposer 106 being replaced with the test interposer 602 of thepresent disclosure. The test interposer 602 is similar to theconventional interposer 106 of FIG. 3 in that in test mode it can passtest stimulus and control inputs 118 from a tester 702 to the testcircuitry 404 and pass test response outputs 120 from the test circuitry404 to the tester 702.

The test interposer 602 of FIGS. 6 and 7 differs from the conventionalinterposer 106 of FIGS. 3 and 5 in that it has additional inputs forinputting 1149.1 TAP input signals (TAPI) from the substrate 608 ortester 702 and an additional output for outputting an 1149.1 TAP outputsignal (TAPO) 606 to the substrate 608 or tester 702. The 1149.1 TAP canbe accessed via TAPI and TAPO to enable test circuitry embedded withintest interposer 602 to test the die, as described below.

FIG. 8 illustrates a first example embodiment of a test interposer 602of the present disclosure shown coupled between a tester or substrate801 and a die 802. Die 802 may be directly coupled to the testinterposer 602 or it may be coupled to the test interposer via TSVs 803of one or more intermediate dies 816 in a die stack. Test interposer 602includes an 1149.1 TAP 804, a stimulus generator circuit 806, a responsecollector circuit 808, multiplexer 810 and multiplexer 812. The TAP hasinputs for a TDI, TCK and TMS signal from TAPI 604 of tester orsubstrate 801 and outputs for a control bus 814 and a TDO signal to TAPO606 of tester or substrate 702. The stimulus generator 806 has inputscoupled to the TAP control bus 814 and stimulus outputs 818 coupled tomultiplexer 810. The response collector has inputs coupled to the TAPcontrol bus 814 and to response outputs 825 on bus 120 from testcircuitry 404 of die 802. Multiplexer 810 has first inputs coupled tothe stimulus outputs 818 of stimulus generator 806, second inputscoupled to stimulus inputs 820 on bus 118 from tester or substrate 801,a control input coupled to TAP control bus 814 and outputs coupled tostimulus inputs 824 on bus 118 to test circuitry 404 of die 802.Multiplexer 812 has first inputs coupled to the TAP control bus 814,second inputs coupled to control inputs 822 on bus 118 from tester orsubstrate 801 and outputs coupled to control inputs 826 on bus 118 totest circuitry 404 of die 802.

The stimulus input signals 820 on bus 118 are removed from bus 118 atpoint 828 and are replaced onto bus 118 at point 830 via output bus 824of multiplexer 810. The stimulus input signals 824 that are replacedonto bus 118 at point 830 may, by control of multiplexer 810, come frombus 820 of bus 118 or from bus 818 from stimulus generator 810.

The control input signals 822 on bus 118 are removed from bus 118 atpoint 832 and are replaced onto bus 118 at point 834 via output bus 812of multiplexer 812. The control input signals 826 that are replaced ontobus 118 at point 834 may, by control of multiplexer 812, come from bus822 of bus 118 or from control bus 814 of TAP 804.

The stimulus and control input signals of bus 118 may be dedicated testinput signals to test circuitry 404 or they may be shared between beingused as test input signals to test circuitry 404 and functional inputsignals to functional circuitry 402. Likewise, the response outputsignals of bus 120 may be dedicated test output signals from testcircuitry 404 or they may be shared between being used as test outputsignals from test circuitry 404 and functional output signals fromfunctional circuitry 402.

The advantage of sharing the stimulus, control and response signals isthat it reduces the number of TSVs that must be implemented in each dieof the die stack, which also reduces the number of connection points 116between the die in the die stack, each of which requires continuitytesting.

If the stimulus 824 and control 826 bus signals are dedicated, they willbe connected directly to the stimulus and control bus signal inputs oftest circuitry 404 as shown in dotted lines 838 and 840, instead ofbeing replaced onto bus 118 at points 830 and 834.

Functional Operation Mode

During functional operation when the test interposer 602 is mounted on asystem substrate 801, the test interposer 602 is controlled by TAP 804to allow the substrate 801 to input functional signals to die 802 viainput bus 118 and receive functional output signals from die 802 viaoutput bus 120. If the stimulus and control test input signals areshared as functional input signals to die 802, as mentioned above,multiplexer 810 will be controlled by TAP bus 814 to couple bus 820 tobus 824 and multiplexer 812 will be control by TAP bus 814 to couple bus822 to bus 826 to provide functional inputs to die 802 on the sharedsignals. If the response test output signals 825 are shared asfunctional output signals from die 802, they will be output to substrate801 via bus 120.

Test Operation Mode 1

During test operation when the test interposer 602 is mounted on asystem substrate 801, a TAP controller 836 connected to the substrate801 can test die 802 by communicating to TAP 804 via the TAPI and TAPIsignals. In response to the communication, TAP 804 outputs control oncontrol bus 814 to couple the stimulus outputs of stimulus generator 806to the stimulus inputs of test circuitry 404 via multiplexer 810 andcouple the TAP control bus 814 to the control inputs of test circuitry404 via multiplexer 812. Once the stimulus and control multiplexers areset, TAP 804 can be controlled by the TAP controller 836 to outputcontrol on bus 814 to; (1) operate the stimulus generator 806 to providetest stimulus data to test circuitry 404, (2) operate the responsecollector 808 to receive test response data from test circuitry 404 and(3) to control the test circuitry 404 to input the test stimulus dataand output the test response data. At the end of test, TAP 804 can becontrolled by the TAP controller 836 to control the response collector808 to output the response test data collected during the test forinspection. Following the test, TAP 804 is controlled by the TAPcontroller 836 to place the test interposer 602 back into its functionalmode to allow die 802 to resume functional input and outputcommunication with substrate 801.

Test Operation Mode 2

During test operation when the test interposer 602 is connected to atester 801 and the test is to be performed by the tester providing thestimulus and control inputs via bus 118 and receiving the responseoutputs via bus 120, the multiplexers 810 and 812 are set to couple thetester provided stimulus and control signals on bus 118 to testcircuitry 404 and the response signals from test circuitry 404 areoutput to the tester via bus 120. In this test operation mode, the testinterposer 602 is set to operate like the conventional interposer 106 ofFIG. 5 during test.

Test Operation Mode 3

During test operation when the test interposer 602 is connected to atester 801, and the test is to be performed by the tester operating TAP804 via the TAPI and TAPO interface, multiplexers 810 and 812 are set byTAP bus 814 to couple the stimulus generator output bus 818 to thestimulus inputs of test circuitry 404 and the TAP control bus 814 to thecontrol inputs of test circuitry 404. Once the stimulus and controlmultiplexers are set, TAP 804 is controlled by the tester 801 to outputcontrol on bus 814 to; (1) operate the stimulus generator 806 to providetest stimulus data to test circuitry 404, (2) operate the responsecollector 808 to receive test response data from test circuitry 404 and(3) to control the test circuitry 404 to input test stimulus data andoutput test response data. At the end of test, TAP 804 can be controlledby the tester 801 to control the response collector 808 to output theresponse test data collected during the test for inspection. Since thistest only requires access to the test interposer’s TAPI and TAPOinterface, the tester 801 may simply be a TAP controller 836.

FIG. 9 illustrates a second example embodiment of a test interposer 602of the present disclosure shown coupled between a tester or substrate801 and a die 802. Die 802 may be directly coupled to the testinterposer 602 or it may be coupled to the test interposer via TSVs 803of one or more intermediate dies 816 in a die stack. Test interposer 602includes an 1149.1 TAP 804, a stimulus generator circuit 902, a controlgenerator circuit 904, a response collector circuit 906, multiplexer 810and multiplexer 812. The TAP has inputs for a TDI, TCK and TMS signalfrom TAPI 604 of tester or substrate 801 and outputs for a control bus814 and a TDO signal to TAPO 606 of tester or substrate 801. Thestimulus generator 902 has inputs coupled to the TAP control bus 814,inputs coupled to control outputs 908 of the control generator 904 andstimulus outputs 910 coupled to multiplexer 810. The response collector906 has inputs coupled to the TAP control bus 814, inputs coupled tocontrol outputs 912 of the control generator 904 and inputs coupled toresponse outputs 825 on bus 120 from test circuitry 404 of die 802. Thecontrol generator 904 has inputs coupled to the TAP control bus 814,control outputs 908 coupled to stimulus generator 902, control outputs912 coupled to response collector 906 and control outputs 914 coupled toinputs of multiplexer 812. Multiplexer 810 has first inputs coupled tothe stimulus outputs 910 of stimulus generator 902, second inputscoupled to stimulus inputs 820 on bus 118 from tester or substrate 801,a control input coupled to TAP control bus 814 and outputs coupled tostimulus inputs 824 on bus 118 to test circuitry 404 of die 802.Multiplexer 812 has first inputs coupled to the control outputs 914 ofcontrol generator 904, second inputs coupled to control inputs 822 onbus 118 from tester or substrate 801 and outputs coupled to controlinputs 826 on bus 118 to test circuitry 404 of die 802.

The stimulus input signals 820 on bus 118 are removed from bus 118 atpoint 828 and are replaced onto bus 118 at point 830 via output bus 824of multiplexer 810. The stimulus input signals 824 that are replacedonto bus 118 at point 830 may, by control of multiplexer 810, come frombus 820 of bus 118 or from bus 910 from stimulus generator 902.

The control input signals 822 on bus 118 are removed from bus 118 atpoint 832 and are replaced onto bus 118 at point 834 via output bus 812of multiplexer 812. The control input signals 826 that are replaced ontobus 118 at point 834 may, by control of multiplexer 812, come from bus822 of bus 118 or from control bus 914 of control generator 904.

The stimulus and control input signals of bus 118 may be dedicated testinput signals to test circuitry 404 or they may be shared between beingused as test input signals to test circuitry 404 and functional inputsignals to functional circuitry 402. Likewise, the response outputsignals of bus 120 may be dedicated test output signals from testcircuitry 404 or they may be shared between being used as test outputsignals from test circuitry 404 and functional output signals fromfunctional circuitry 402.

The advantage of sharing the stimulus, control and response signals isthat it reduces the number of TSVs that must be implemented in each dieof the die stack, which also reduces the number of connection points 116between the die in the die stack, each of which requires continuitytesting.

If the stimulus 824 and control 826 bus signals are dedicated, they willbe connected directly to the stimulus and control bus signal inputs oftest circuitry 404 as shown in dotted lines 838 and 840, instead ofbeing replaced onto bus 118 at points 830 and 834.

Functional Operation Mode

During functional operation when the test interposer 602 is mounted on asystem substrate 801, the test interposer 602 is controlled by TAP 804to allow the substrate 801 to input functional signals to die 802 viainput bus 118 and receive functional output signals from die 802 viaoutput bus 120. If the stimulus and control test input signals areshared as functional input signals to die 802, as mentioned above,multiplexer 810 will be controlled by TAP bus 814 to couple bus 820 tobus 824 and multiplexer 812 will be control by TAP bus 814 to couple bus822 to bus 826 to provide functional inputs to die 802 on the sharedsignals. If the response test output signals 825 are shared asfunctional output signals from die 802, they will be output to substrate801 via bus 120.

Test Operation Mode 1

During test operation when the test interposer 602 is mounted on asystem substrate 801, a TAP controller 836 connected to the substrate801 can test die 802 by communicating to TAP 804 via the TAPI and TAPIsignals. In response to the communication, TAP 804 outputs control oncontrol bus 814 to couple the stimulus outputs of stimulus generator 902to the stimulus inputs of test circuitry 404 via multiplexer 810 andcouple the control generator 904 control bus 914 to the control inputsof test circuitry 404 via multiplexer 812. Once the stimulus and controlmultiplexers are set, TAP 804 can be controlled by the TAP controller836 to output control on bus 814 to enable the control generator 904.When control generator 904 is enabled, it; (1) outputs control on bus908 to operate the stimulus generator 902 to provide test stimulus datato test circuitry 404, (2) outputs control on bus 912 to operate theresponse collector 908 to receive test response data from test circuitry404 and (3) outputs control on bus 914 to operate the test circuitry 404to input the test stimulus data and output the test response data. Atthe end of test, TAP 804 can be controlled by the TAP controller 836 tocontrol the response collector 908 to output the response test datacollected during the test for inspection. Following the test, TAP 804 iscontrolled by the TAP controller 836 to place the test interposer 602back into its functional mode to allow die 802 to resume functionalinput and output communication with substrate 801.

Test Operation Mode 2

During test operation when the test interposer 602 is connected to atester 801 and the test is to be performed by the tester providing thestimulus and control inputs via bus 118 and receiving the responseoutputs via bus 120, the multiplexers 810 and 812 are set to couple thetester provided stimulus and control signals on bus 118 to testcircuitry 404 and the response signals from test circuitry 404 areoutput to the tester via bus 120. In this test operation mode, the testinterposer 602 is set to operate like the conventional interposer 106 ofFIG. 5 during test.

Test Operation Mode 3

During test operation when the test interposer 602 is connected to atester 801, and the test is to be performed by the tester operating TAP804 via the TAPI and TAPO interface, multiplexers 810 and 812 are set byTAP bus 814 to couple the stimulus generator output bus 910 to thestimulus inputs of test circuitry 404 and the control generator outputbus 914 to the control inputs of test circuitry 404. Once the stimulusand control multiplexers are set, TAP 804 can be controlled by the TAPcontroller 836 to output control on bus 814 to enable the controlgenerator 904. When control generator 904 is enabled, it; (1) outputscontrol on bus 908 to operate the stimulus generator 902 to provide teststimulus data to test circuitry 404, (2) outputs control on bus 912 tooperate the response collector 908 to receive test response data fromtest circuitry 404 and (3) outputs control on bus 914 to operate thetest circuitry 404 to input the test stimulus data and output the testresponse data. At the end of test, TAP 804 can be controlled by thetester 801 to control the response collector 808 to output the responsetest data collected during the test for inspection. Since this test onlyrequires access to the test interposer’s TAPI and TAPO interface, thetester 801 may simply be a TAP controller 836.

FIG. 10 illustrates TAP 804 and its control bus 814 connections tocontrol generator 904, response collector 808/906 and stimulus generator806/902. The TAP is a well known test interface that operates accordingto the TAP state diagram of FIG. 11 . The TAP includes a Tap StateMachine (TSM) 1002, an instruction register 1004, data registers 1006and a TDO output multiplexer 1008. In response to the TCK and TMS inputof bus 604, the TSM may be in a reset state, a run test/idle state, dataregister scanning states or instruction register scanning states as seenin FIG. 11 . During instruction register scanning states, the TSMoutputs control (CTL) to scan an instruction into instruction register1004 from TDI to TDO. During data register scanning states, the TSMoutputs CTL to scan data into a data register 1006, selected by theinstruction register output (IRO) bus of the instruction register, fromTDI to TDO. As seen the TAP 804 interfaces with control generator,response collector and stimulus generator via the TDI, CTL, IRO and TDOsignals of the control bus 814. When an instruction is loaded into theinstruction register to select one of the control generator, responsecollector and stimulus generator, it can be scanned from TDI to TDO.Multiplexer 1008 is controlled by the IRO output bus to couple the TDOoutput of a selected data register, control generator, responsecollector or stimulus generator to the TDO 606 output of the TAP.

Scan Test Compression Example Using The Test Interposer

FIG. 12 illustrates a die 1202 containing a scan test compressioncircuit 1204 coupled to a tester 1206 via a test interposer 602 eitherdirectly or indirectly via TSVs 803 of intermediate die 816. Testcompression circuits are well known and widely used in the industry. Inresponse to control inputs, they input compressed stimulus data andoutput compacted response data.

If the test interposer 602 is set to allow the compressed stimulus andcontrol inputs to be input from the tester 1206, multiplexers 810 and812 will be controlled by the TAP 804 to couple compressed stimulusinputs from bus 118 to the compressed stimulus inputs of the testcompression circuit and control inputs 822 from bus 118 to the controlinputs of the test compression circuit. The compacted response is outputto the tester on bus 120.

If the test interposer 602 is set to allow the compressed stimulus andcontrol inputs to be input from the stimulus generator 806 and TAPcontrol bus 814, respectively, multiplexers 810 and 812 will becontrolled by the TAP 804 to couple compressed stimulus outputs 818 fromstimulus generator 806 to the compressed stimulus inputs of the testcompression circuit and the TAP control bus 814 to the control inputs ofthe test compression circuit. The compacted response is output to theresponse collector 808 via bus 825 from bus 120.

FIG. 13 illustrates an example test compression circuit which includes adecompressor 1302, scan paths 1304, compactor 1306 and combination logic1308 to be tested. The decompressor 1302 inputs a small number ofcompressed stimulus data inputs and decompresses them into a largenumber scan inputs to the scan paths 1304. The compactor 1306 inputs alarge number scan outputs from the scan paths 1304 and compacts themdown to a smaller number of compacted response outputs. The scan paths1304 outputs parallel stimulus to the combinational logic and receiveparallel response from the combinational logic. The decompressor, thescan paths and optionally, as indicated in dotted line, the compactoroperate in response to the control inputs, which in this exampleincludes at least a scan enable (SEN) input and a scan clock (SCK)input.

FIG. 14 illustrates one example of how the TAP 804 may control thestimulus generator 806 that provides compressed stimulus data to a testcompression circuit 1204 of FIG. 12 and the response collector 808 thatreceives compacted response data from the test compression circuit 1204of FIG. 12 . As seen the TAP control bus 814 of FIG. 10 is expanded toinclude a SEN, a test enable (TEN) and a SCK signal. The SEN, TEN andSCK signals are input to the stimulus generator 806 and the responsecompactor 808. The SEN and SCK signals are output to the testcompression circuit of FIG. 13 via multiplexer 812 of FIG. 12 . The SENand SCK signals come from the TSM 1002 of FIG. 10 and the TEN signalcomes from the IRO bus of the instruction register 1004 of FIG. 10 . TheTEN signal is set to enable the stimulus generator and responsecollector whenever the test compression circuit is selected for testing.

When the TAP is in the Capture-DR state of FIG. 11 the SEN signal is set(SEN=0) and a SCK is produced to cause the scan paths 1304 to captureresponse data from the combinational logic 1308. When the TAP is in theShift-DR state of FIG. 11 the SEN signal is set (SEN=1) and SCKs areproduced to cause the scan paths 1304 to shift data in and out. Also inthe Shift-DR state, the stimulus generator outputs compressed stimulusto the test compression circuit and response collector inputs compactedresponse from the test compression circuit. In some implementations a“clock leaker” circuit 1402 may be optionally placed in the SCK signalpath to allow a functional clock (FCK) to be leaked (i.e. gated) to thetest compression circuit, stimulus generator and response collector inplace of and in response to a produced SCK output from the TAP.

FIG. 15 illustrates a first example implementation of a stimulusgenerator 806 for outputting compressed stimulus to a test compressioncircuit. The stimulus generator includes a stimulus controller 1502 andan N-bit wide stimulus memory 1504. The memory may be a ROM or a RAM. Ifit is a RAM memory a register 1506 will be provided on the memory toallow the TAP to write compressed stimulus data into the memory viacontrol bus 814. When TEN is set and the TAP 804 is in the Shift-DRstate (SEN=1), stimulus controller 1502 increments the memory address(ADD) during each SCK to output N-bit wide compressed stimulus to anN-bit wide test compression circuit. When TEN is set and the TAP 804 isnot in the Shift-DR state (SEN=0) it ceases incrementing the memoryaddress. In this example, the width (N) of the data bus output from thememory is designed to be equal to the width (N) of the compressedstimulus input to the test compression circuit.

FIG. 16 illustrates a second example implementation of a stimulusgenerator 806 for outputting compressed stimulus to a test compressioncircuit. The stimulus generator includes a stimulus controller 1602, anN-bit wide stimulus memory 1504 which could be a ROM or RAM memory andan N to M bit width converter 1604. When TEN is set and the TAP 804 isin the Shift-DR state (SEN=1), stimulus controller 1602 outputs control(CTL) to cause the N to M converter to convert the wider N bit memoryoutput bus to a narrower M bit bus that is input to the test compressioncircuit. After the N to M bit conversion is complete the stimuluscontroller increments the memory address to output the next N bit widecompressed stimulus pattern to the N to M converter. The stimuluscontroller is designed to perform the address increment operation suchthat it does not interrupt the M bit wide compressed stimulus output tothe test compression circuit. When TEN is set and the TAP 804 is not inthe Shift-DR state (SEN=0), the stimulus controller ceases controllingthe N to M bit converter and incrementing the memory address. In thisexample, a larger N bit wide data bus output from the memory is adaptedby the N to M bit converter to be equal to a smaller M bit wide input toa test compression circuit.

FIG. 17 illustrates a first example of an N to M bit width converter1604 which includes a shift register 1702. The shift register receivesload control (LDC) input and clock (CLK) input from controller 1602. TheCLK input is synchronized with the SCK when the TAP is in the Shift-DRstate. The LDC input causes the shift register to load the N bit widestimulus data from the stimulus memory 1504 and the CLK input causes theshift register to serially output the N bit wide stimulus data on asingle M wide output to a single M wide input of a test compressioncircuit.

FIG. 18 illustrates a second example of an N to M bit width converter1604 which includes, in this example, two shift registers 1702. Theshift registers receive the LDC and CLK input from controller 1602. TheCLK input is synchronized with the SCK when the TAP is in the Shift-DRstate. The LDC input causes each of the shift registers tosimultaneously load separate halves (N/2) of the N bit wide stimulusdata from the stimulus memory 1504 and the CLK input causes the shiftregisters to serially output the separate N/2 halves on a pair of Moutputs to a pair of M inputs of a test compression circuit. While thisexample shows two shift registers providing two M outputs, any number ofshift registers and corresponding M outputs may be provided.

FIG. 19 illustrates a third example of an N to M bit width converter1604 which includes a multiplexer 1902. The multiplexer receives select(SEL) input from controller 1602. The SEL input causes the multiplexerto alternate between outputting separate halves (N/2) of the N bit wideoutput from the stimulus memory 1504 to an M bit wide input to a testcompression circuit, where M=N/2. While this example shows themultiplexer having two N/2 input busses that selectively drive the Moutput bus, the multiplexer could have any number of lesser width inputbusses (N/X) that selectively drive a correspondingly lesser width Moutput bus.

FIG. 20 illustrates a fourth example of an N to M bit width converter1604 which includes tri-state buffers 2002 and 2004. Buffer 2002receives a first enable (EN1) input from controller 1602 and buffer 2004receives a second enable input (EN2) from controller 1602. When EN1 isactive, buffer 2002 outputs a first half (N/2) of the N bit wide busfrom memory 1504 to an M bit wide input to a test compression circuit.When EN2 is active, buffer 2004 outputs a second half (N/2) of the N bitwide bus from memory 1504 to the M bit wide input of the testcompression circuit. While this example shows two buffers providing twoseparate N/2 wide sections of the N wide memory output bus to acorrespondingly wide M output bus, any number of buffers could be usedto provide any number of separate N/X wide sections of the N output busto a correspondingly wide M output bus.

FIG. 21 illustrates a first example implementation of a responsecollector 808 for receiving compacted response from a test compressioncircuit. The response collector includes a response controller 2102 andan N-bit wide response memory 2104, such as a RAM memory. A register2106 will be provided on the memory to allow the TAP to read out thecompacted response stored in the memory after the test via control bus814. When TEN is set and the TAP 804 is in the Shift-DR state (SEN=1),response controller 2102 outputs a write (WRT) signal to the memory tocause the memory to store compacted response data from a testcompression circuit into the currently addressed memory location.Following the write operation, the response controller increments thememory address (ADD) to the next location to be written too. Eachaddressed memory location is written to during each SCK while the TAP isin the Shift-DR state. When the TAP 804 is not in the Shift-DR state(SEN=0), the response controller ceases the write and addressincrementing operations. In this example, the width (N) of data businput to the memory is designed to be equal to the width (N) of thecompacted response output from the test compression circuit.

FIG. 22 illustrates a second example implementation of a responsecollector 808 for receiving compacted response from a test compressioncircuit. The response collector includes a response controller 2202, anN-bit wide response memory 2104 and an M to N bit width converter 2204.When TEN is set and the TAP 804 is in the Shift-DR state (SEN=1),response controller 2202 outputs control (CTL) to cause the M to Nconverter to convert the smaller M-bit wide output bus from the testcompression circuit to the wider N-bit wide input bus to the memory.After the M to N conversion is complete the response controller outputsa write (WRT) signal to store the N-bit wide response pattern in thecurrently addressed memory location, then increments the memory address(ADD) to the next location to be written to. The response controller isdesigned to perform the memory write and address increment operationssuch that it does not interrupt the M to N bit conversion operation ofthe M to N bit converter. When TEN is set and the TAP 804 is not in theShift-DR state (SEN=0), the response controller ceases controlling the Mto N bit converter and ceases the write and address incrementingoperations. In this example, the larger N bit wide data bus input to thememory is adapted by the M to N bit converter to receive the smaller Mbit wide output from a test compression circuit.

FIG. 23 illustrates a first example of an M to N bit width converter2204 which includes a shift register 2302. The shift register receivesthe CLK input from controller 1602. The CLK input is synchronized withthe SCK when TEN is set and the TAP is in the Shift-DR state (SEN=1).The CLK input causes the shift register to input a single compactedresponse input (M) from a single compacted response output (M) of a testcompression circuit. When the shift register fills, the responsecontroller outputs a write (WRT) signal to cause memory 2104 to load theparallel output of the shift register into the currently addressedmemory location. Following the write operation, the response controllerincrements the memory address (ADD). This serial input and paralleloutput operation repeats while the TAP is in the Shift-DR state. Whenthe TAP 804 exits the Shift-DR state it ceases the serial input andparallel write operations.

FIG. 24 illustrates a second example of an M to N bit width converter2204 which includes a pair of shift registers 2302. The shift registersreceive the CLK input from controller 1602. The CLK input issynchronized with the SCK when TEN is set and the TAP is in the Shift-DRstate (SEN=1). The CLK input causes the shift registers to input a pairof compacted response inputs (M) from a pair of compacted responseoutputs (M) of a test compression circuit. When the shift registersfill, the response controller outputs a write (WRT) signal to causememory 2104 to load the parallel outputs of the shift registers into thecurrently addressed memory location. Following the write operation, theresponse controller increments the memory address (ADD). This serialinput and parallel output operation repeats while the TAP is in theShift-DR state. When the TAP 804 exits the Shift-DR state it ceases theserial input and parallel write operations. While this example shows twoshift registers providing inputs from two M outputs of a testcompression circuit to two N/2 inputs of the memory, any number of shiftregisters (X) may be employed to support a corresponding number ofinputs (X) from a test compression circuit. Each shift register wouldprovide an N/X wide input bus to the N wide input bus of memory 2104.

FIG. 25 illustrates a third example implementation of a responsecollector 808 for receiving N-bit wide compacted response from a testcompression circuit. The response collector includes a responsecontroller 2502, a compare circuit 2504 and memory 2506 for storingN-bit wide expected compacted response (ECR) data. The memory could be aROM or RAM. If it is a RAM, it will be interfaced to TAP 804 via controlbus 814 to allow loading the ECR data as described in regard to memory1504 of FIG. 15 . When TEN is set and the TAP 804 is in the Shift-DRstate (SEN=1), response controller 2502 outputs a clock (CLK) signal tothe compare circuit to cause the compare circuit to compare thecompacted response output from a test compression circuit against theECR output from a currently addressed location in memory 2506. The CLKsignal is synchronized with the SCK signal. Following the compareoperation, the response controller increments the memory address (ADD)to output the next ECR data to the compare circuit. The ADD output fromresponse controller 2502 is also input to compare circuit 2504 to allowstoring the ECR address where a comparison failure occurs. This CLK andADD sequence repeats while the TAP is in the Shift-DR state. When theTAP 804 is not in the Shift-DR state (SEN=0), the response controllerceases producing the CLK and ADD signals. At the end of test, thecompare circuit is accessed via control bus 814 to unload the results ofthe test which includes any failing bit(s) locations and the ECRaddress(s) where the failure(s) occurred. As seen in dotted line, an Mto N converter 2204 may be used in response collector 808 and controlled(CTL) by the response controller 2502 as described in FIGS. 22-24 .

FIG. 26 illustrates an example implementation of compare circuit 2504which includes a comparator 2602, pass/fail (PF) data and address memory2604 and a register for allowing the memory 2604 to be accessed by theTAP 804 via bus 814. The comparator inputs the N-bit wide compactedresponse (CR) and ECR buses and outputs an N-bit wide PF bus and a failsignal. Memory 2604 inputs the PF bus, the fail signal and the ADDoutput from the response controller 2502. If the fail signal does notindicate a compare failure, memory 2604 does not respond to the CLKinput. If the fail signal indicates a compare failure, memory 2604responds to the CLK input to store the PF bus and the ADD from responsecontroller 2502. Before the test starts the memory is initialized by theTAP via control bus 814. At the end of test, the contents of memory 2604is read out via TAP control bus 814 to detect any failing PF bits andthe address(s) where the failure(s) occurred.

FIG. 27 illustrates an example implementation of comparator 2602. Thecomparator includes and N XOR gates and an OR gate. Each of the N XORgate inputs a unique one of the N CR and N ECR inputs and produces aunique PF output. The OR gate inputs the N PF outputs and outputs thefail signal. If any one or more of the N PF outputs indicate a comparefailure (a high in this example), the OR gate outputs a fail signal tomemory 2604.

FIG. 28 illustrates a fourth example implementation of a responsecollector 808 for receiving N-bit wide compacted response from a testcompression circuit. The response collector includes an N-bit widemultiple input signature register (MISR). MISRs are LFSR based circuitsthat compress parallel inputs into a signature. The MISR is interfacedto control bus 814 to allow it to be accessed by the TAP 804. When TENis set and the TAP 804 is in the Shift-DR state (SEN=1), MISR 2802inputs and compresses the N-bit output from a test compression circuitduring each SCK signal output from TAP 804. When the TAP 804 is not inthe Shift-DR state (SEN=0), the MISR ceases inputting and compressingthe N-bit output from the test compression circuit. At the end of test,the signature contained in the MISR is read out via control bus 814 fromTAP 804.

FIG. 29 illustrates a first example of a die 1202 coupled eitherdirectly or indirectly, through TSVs 803 of intermediate die 816, to thetest interposer 602 of FIG. 12 . The test interposer 602 is connected tothe TAPI and TAPO signals of a TAP controller 2904. In this example,multiplexer 810 is set to couple the outputs of stimulus generator 806to the compressed stimulus inputs of a test compression circuit 1204 indie 1202, multiplexer 812 is set to couple the TAP control bus 814 tothe control inputs of the test compression circuit 1204 and thecompacted response outputs from test compression circuit 1204 are inputto response collector 808. The stimulus generator 806 and responsecollector may be, but are not limited to being, any of the previouslydescribed stimulus generator 806 and response collector 808 circuits.

During test, the TAP controller 2904 operates the TAP 804 to inputcompressed stimulus to the test compression circuit from stimulusgenerator 806, input compacted response from the test compressioncircuit to response collector 808 and to control the operation of thetest compression circuit via TAP control bus 814. At the end of test,the TAP controller 2904 accesses the response collector 808 via bus 814to read out the test response results contained therein.

FIG. 30 illustrates the state transitions (see FIG. 11 ) the TAP 804loops 3002 through during the test. As seen the TAP loops through atleast the Select-DR state (SELDR) to the Capture-DR state (CDR), fromthe CDR state to the Shift-DR state (SDR), from the SDR state to theExit1-DR state (X1DR), from the X1DR state to the Update-DR state (UDR)and back to the SELDR state. This state transition loop repeats untilthe test is complete. In the CDR state, the scan paths 1304 of the testcompression circuit are controlled to capture response data fromcombinational logic 1308 of FIG. 13 . In the SDR state, the stimulusgenerator 806 is controlled to output compressed stimulus to thedecompressor 1302 of the test compression circuit, the responsecollector 808 is controlled to input compacted response from compactor1306 of the test compression circuit and the scan paths 1304 arecontrolled to shift data in from the decompressor and out to thecompactor.

FIG. 31 illustrates a second example of a die 1202 coupled eitherdirectly or indirectly through TSVs 803 of intermediate die 816, to atest interposer 602. The test interposer 602 is connected to a tester3102 providing stimulus inputs 118 and TAPI and TAPO signals to the testinterposer’s TAP 804. In this example, multiplexer 810 is set to couplethe stimulus inputs 118 from tester 3102 to the compressed stimulusinputs of a test compression circuit 1204 in die 1202, multiplexer 812is set to couple the TAP control bus 814 to the control inputs of thetest compression circuit 1204 and the compacted response outputs fromtest compression circuit 1204 are input to response collector 808. Theresponse collector may be, but is not limited to being, any of thepreviously described response collector 808 circuits.

During test, the tester 3102 operates the TAP 804 to input compressedstimulus inputs 118 from tester 3102 to test the compression circuit,input compacted response from the test compression circuit to responsecollector 808 and to control the operation of the test compressioncircuit via TAP control bus 814. At the end of test, the tester 3102accesses the response collector 808 via bus 814 to read out the testresponse results contained therein.

FIG. 32 illustrates a state transition loop the TAP 804 may go throughduring the test. The state transition loop is the same as described inregard to FIGS. 29 and 30 . In the CDR state, the scan paths 1304 of thetest compression circuit are controlled to capture response data fromcombinational logic 1308 of FIG. 13 . In the SDR state, the testerprovides stimulus input 118 to the decompressor 1302 of the testcompression circuit, the response collector 808 is controlled to inputcompacted response from compactor 1306 of the test compression circuitand the scan paths 1304 are controlled to shift data in from thedecompressor and out to the compactor. As seen, this test method issimilar to the test method of FIGS. 29 and 30 , with the exception thatthe tester 3102 provides the compressed stimulus inputs to the testcompression circuit instead of the stimulus generator 806.

FIG. 33 illustrates a die 1202 containing a scan test compressioncircuit 1204 coupled to a tester 1206 via a test interposer 602 of FIG.12 , either directly or indirectly via TSVs of intermediate die 816. Thetest interposer includes a TAP 804, stimulus generator 902, controlgenerator 904, response collector 906, multiplexer 810 and multiplexer812. The control generator can be controlled by the TAP via bus 814 tooutput control signals 3302 to stimulus generator 902, control signals3304 to multiplexer 812 and control signals 3306 to response collector906.

If the test interposer 602 is set to allow the compressed stimulus andcontrol inputs to be input from the tester 1206, multiplexers 810 and812 will be controlled by TAP 804 to couple compressed stimulus inputsfrom bus 118 to the compressed stimulus inputs of the test compressioncircuit and control inputs from bus 118 to the control inputs of thetest compression circuit. The compacted response is output to the testeron bus 120.

If the test interposer 602 is set to allow the compressed stimulus andcontrol inputs to be input from the stimulus generator 902 and controlgenerator 904, respectively, multiplexers 810 and 812 will be controlledby TAP 804 to couple the compressed stimulus outputs from stimulusgenerator 902 to the compressed stimulus inputs 824 of the testcompression circuit and control outputs from the control generator 904to the control inputs 826 of the test compression circuit. The compactedresponse output is input to the response collector 906 via bus 825 frombus 120.

FIG. 34 illustrates one example of how the TAP 804 may control theoperation of control generator 904. As seen the TAP control bus 814 ofFIG. 10 is expanded to include a TEN, a Run Test Idle (RTI), and a TCKsignal. The RTI signal is output from the TAP 804 when the TSM 1002 ofFIG. 10 is in the Run Test/Idle state of FIG. 11 . The TEN signal comesfrom the IRO bus of the instruction register 1004 of FIG. 10 . The TCKsignal comes from TAPI bus 604.

To enable the control generator 904 the TAP is accessed via TAPI andTAPO to load an instruction into the TAP instruction register 1002,which sets the TEN signal. Next, the TAP is transitioned into the RunTest/Idle state of FIG. 11 which sets the RTI signal. When TEN and RTIare both set, the control generator responds to the TCK input to operatethe output stimulus control bus (SCB) 3302 to stimulus generator 902,the SEN and SCK signals 3304 to multiplexer 812 and the response controlbus (RCB) 3306 to response collector 906. In response to the SCB, thestimulus generator outputs compressed stimulus to the test compressioncircuit. In response to the RCB, the response collector inputs compactedresponse from the test compression circuit. In response to the SEN andSCK signals, the test compression circuit inputs the compressed stimulusand outputs compacted response when SEN is set (SEN=1) and capturesresponse data from combinational logic when SEN is not set (SEN=0).

FIG. 35 illustrates a first example implementation of a stimulusgenerator 902 for outputting compressed stimulus to a test compressioncircuit. The stimulus generator 902 operates as described in thestimulus generator 806 of FIG. 15 . The only difference between thestimulus generator 806 of FIG. 15 and the stimulus generator 902 of FIG.35 is that the ADD inputs come from control generator 904 via SCB 3302.

FIG. 36 illustrates a second example implementation of a stimulusgenerator 902 for outputting compressed stimulus to a test compressioncircuit. The stimulus generator 902 operates as described in thestimulus generator 806 of FIG. 16 . The only difference between thestimulus generator 806 of FIG. 16 and the stimulus generator 902 of FIG.36 is that the ADD and CTL inputs come from control generator 904 viaSCB 3302.

FIG. 37 illustrates a first example implementation of a responsecollector 906 for inputting compacted response from a test compressioncircuit. The response collector 906 operates as described in theresponse collector 808 of FIG. 21 . The only difference between theresponse collector 808 of FIG. 21 and the response collector 906 of FIG.37 is that the ADD and WR inputs come from control generator 904 via RCB3306.

FIG. 38 illustrates a second example implementation of a responsecollector 906 for inputting compacted response from a test compressioncircuit. The response collector 906 operates as described in theresponse collector 808 of FIG. 22 . The only difference between theresponse collector 808 of FIG. 22 and the response collector 906 of FIG.38 is that the ADD and WR inputs come from control generator 904 via RCB3306.

FIG. 39 illustrates a third example implementation of a responsecollector 906 for inputting compacted response from a test compressioncircuit. The response collector 906 operates as described in theresponse collector 808 of FIG. 25 . The only difference between theresponse collector 808 of FIG. 25 and the response collector 906 of FIG.39 is that the ADD, CLK and CTL inputs come from control generator 904via RCB 3306.

FIG. 40 illustrates a fourth example implementation of a responsecollector 906 for inputting compacted response from a test compressioncircuit. The response collector 906 operates as described in theresponse collector 808 of FIG. 28 . The only difference between theresponse collector 808 of FIG. 28 and the response collector 906 of FIG.40 is that the TEN input is not required and the SEN and SCK inputs comefrom control generator 904 via RCB 3306.

FIG. 41 illustrates an example of a die 1202 coupled either directly orindirectly, through TSVs 803 of intermediate die 816, to the testinterposer 602 of FIG. 33 . The test interposer 602 is connected to theTAPI and TAPO signals of a TAP controller 2904. In this example,multiplexer 810 is set to couple the outputs of stimulus generator 902to the compressed stimulus inputs of a test compression circuit 1204 indie 1202, multiplexer 812 is set to couple the outputs of controlgenerator 904 to the control inputs of the test compression circuit 1204and the compacted response outputs from test compression circuit 1204are input to response collector 906. The stimulus generator 902, controlgenerator 904 and response collector 906 may be, but are not limited tobeing, any of the previously described stimulus generators 902, controlgenerator 904 and response collector 906 circuits.

As seen in FIG. 42 , the test begins by loading a test instruction intothe TAP 804 via the TAPI and TAPO buses to set the TEN signal. Afterloading the instruction, the TAP is transitioned to the Run Test/Idle(RTI) state to enable the control generator 904. While the TAP is in theRTI state, the control generator 904 operates in at least a first state4202 and a second state 4204. In state 4202, the control generatorcontrols the stimulus generator 902 via bus 3302 to input compressedstimulus to the test compression circuit controls the response collector906 via bus 3306 to input compacted response from the test compressioncircuit and controls the test compression circuit via bus 3304 to inputthe compressed inputs and output the compacted outputs. In state 4204,the control generator controls the test compression circuit via bus 3304to capture response output from combinational logic. The controlgenerator transitions between states 4202 and 4204 while the TAP is inthe RTI state. The test ends when the TAP transitions from the RTIstate. At the end of test, the TAP is accessed via the TAPI and TAPObuses to unload the test results stored in the response collector 906.

Testable Memory Example Using The Test Interposer

FIG. 43 illustrates a die 4302 containing a testable memory 4304 coupledto a tester 1206 via a test interposer 602, either directly orindirectly via TSVs 803 of intermediate die 816. The test interposerincludes a TAP 804, stimulus generator 902, control generator 904,response collector 906, multiplexer 810 and multiplexer 812. The controlgenerator can be controlled by the TAP via bus 814 to output controlsignals 3302 to stimulus generator 902, control signals 3304 tomultiplexer 812 and control signals 3306 to response collector 906.

If the test interposer 602 is set to allow the memory 4304 to be testedby the tester 1206, multiplexer 810 is controlled by TAP 804 to inputdata and address stimulus 824 to the memory from tester 1206 via bus 118and multiplexer 812 is controlled by the TAP 804 to input test control826 to the memory from tester 1206 via bus 118. The data response fromthe memory is output to tester 1206 via bus 120.

If the test interposer 602 is set to allow the memory to be tested bythe stimulus generator 902 and control generator 904, multiplexers 810and 812 will be controlled by TAP 804 to couple the data and addressstimulus output from the stimulus generator and the test control outputfrom the control generator to the memory via buses 824 and 826. The dataresponse from the memory is input to the response collector 906 via bus825 from bus 120.

FIG. 44 illustrates an example of a testable memory 4304 that includes aread/write memory 4402, a data input multiplexer 4404, address inputmultiplexer 4406, read control multiplexer 4408 and a write controlmultiplexer 4410. Memory 4402 has a data input (DI) bus, an address (A)input bus, a read (RD) input signal, a write (WR) input signal and adata output (DO) bus. Multiplexer 4404 inputs a functional data bus, adata stimulus bus 824, a TEN signal from bus 826 and outputs a data busto the DI of the memory. Multiplexer 4406 inputs a functional addressbus, an address stimulus bus 824, the TEN signal and outputs an addressbus to the address (A) input bus of the memory. Multiplexer 4408 inputsa functional read (FRD) signal, a test read (TRD) signal from bus 826,the TEN signal and outputs a read signal to the RD input of the memory.Multiplexer 4410 inputs a functional write (FWR) signal, a test write(TWR) signal from bus 826, the TEN signal 826 and outputs a write signalto the WR input of the memory. During functional operation, the TENsignal controls the multiplexers to couple the memory to the functionaldata bus, functional address bus, FRD signal and FWR signal. During testoperation, the TEN signal controls the multiplexers to couple the memoryto the data stimulus bus, address stimulus bus and the TRD and TWRsignals.

FIG. 45 illustrates one example of how the TAP 804 may control theoperation of the control generator 904 of FIG. 43 . As seen the TAPcontrol bus 814 of FIG. 10 is expanded to include the TEN, RTI and TCKsignals described in FIG. 34 . To enable the control generator 904, theTAP is accessed via TAPI and TAPO to load an instruction into the TAPinstruction register 1002, which sets the TEN signal. Next, the TAP istransitioned into the Run Test/Idle state which sets the RTI signal.When TEN and RTI are both set, the control generator responds to the TCKinput to; (1) operate a stimulus address control (SAC) bus 3302 to amemory address generator 4502 in stimulus generator 902, (2) operate astimulus data control (SDC) bus 3302 to a memory data generator 4504 instimulus generator 902, (3) operate the TEN, TRD and TWR control signals3304 to memory 4304 and (4) operate the response control bus (RCB) 3306to response collector 906. Response collector 906 may be, but is notlimited to being, any of the described response collector circuits ofFIGS. 37-40 .

When the SAC bus is operated, the memory address generator 4502 outputsaddress stimulus to memory 4304. When the SDC bus is operated, thememory data generator 4504 outputs data stimulus to memory 4304. Theoutput data stimulus may be any type, such as but not limited to,walking ones, walking zeros and/or checkerboard patterns. When the TENand TWR signals are operated, test data is written to the memory. Whenthe TEN and TRD signals are operated, test data is read from the memory.When the RCB is operated, the response collector inputs the test datafrom the memory.

FIG. 46 illustrates an example of a die 4302 coupled either directly orindirectly, through TSVs 803 of intermediate die 816, to the testinterposer 602 of FIG. 43 . The test interposer 602 is connected to theTAPI and TAPO signals of a TAP controller 2904. In this example,multiplexer 810 is set to couple the outputs of stimulus generator 902to the data and address stimulus inputs of a testable memory 4304 in die4302, multiplexer 812 is set to couple the outputs of control generator904 to the control inputs of the testable memory 4304 and the dataresponse outputs from testable memory 4304 are input to responsecollector 906. The stimulus generator 902 and control generator 904 maybe designed in any suitable manner to achieve the data and addressstimulus input testing requirements of memory 4304. The responsecollector 906 may be, but is not limited to being, any of the previouslydescribe response circuits 906.

As seen in FIG. 47 , the test begins by loading a test instruction intothe TAP 804 to set the TEN signal. After loading the instruction, theTAP is transitioned to the Run Test/Idle state to set the RTI signal toenable the control generator 904. While the TAP is in the RTI state, thecontrol generator 904 operates in at least a first state 4702 and asecond state 4704. In the first state 4702, the control generator 904operates stimulus generator 902 via the SAC and SDC buses 3302 togenerate data and address stimulus to memory 4304 and operates the TENand TWR signals of bus 3304 to write the data stimulus into the memory.In the second state 4704, the control generator 904 operates stimulusgenerator 902 via the SAC bus to generate address stimulus to memory4304, operates the TEN and TRD signals of bus 3304 to read the dataresponse from the memory and operates the response collector 906 toinput the data response from the memory. The control generator 904 maytransition between states 4702 and 4704 in any desired manner. Forexample, state 4702 may write data to a single memory location thentransition to state 4704 to read back the data from the single memorylocation, or state 4702 may write data to all memory locations thentransition to state 4704 and read back the data from all memorylocations.

Testable ADC Example Using The Test Interposer

FIG. 48 illustrates a die 4802 containing a testable analog to digitalconverter (ADC) 4804 coupled to a tester 1206 via a test interposer 602,either directly or indirectly via TSVs 803 of intermediate die 816. Thetest interposer includes a TAP 804, stimulus generator 902, controlgenerator 904, response collector 906, analog switch 4806 andmultiplexer 812. The control generator can be controlled by the TAP viabus 814 to output control signals 3302 to stimulus generator 902,control signals 3304 to multiplexer 812 and control signals 3306 toresponse collector 906.

If the test interposer 602 is set to allow the ADC 4804 to be tested bythe tester 1206, switch 4806 is controlled by TAP 804 to input analogstimulus 824 to the ADC from tester 1206 via bus 118 and multiplexer 812is controlled by the TAP 804 to input test control 826 to the ADC fromtester 1206 via bus 118. The digital response from the ADC is output totester 1206 via bus 120.

If the test interposer 602 is set to allow the ADC to be tested by thestimulus generator 902 and control generator 904, switch 4706 andmultiplexer 812 will be controlled by TAP 804 to couple the analogstimulus output from the stimulus generator and the test control outputfrom the control generator to the ADC via buses 824 and 826. The digitalresponse from the ADC is input to the response collector 906 via bus 825from bus 120.

FIG. 49 illustrates an example of a testable ADC 4804 that includes anADC 4902, an analog input switch 4904, and a control input multiplexer4906. ADC 4902 has an analog input, control (CTL) input(s), and digitaloutputs. Switch 4904 inputs a functional analog signal, an analogstimulus signal from bus 824, a TEN signal from bus 826 and outputs ananalog signal to the analog input of the ADC. Multiplexer 4906 inputsfunctional control (FCTL), test control (TCTL) from bus 826, the TENsignal and outputs control to the CTL input(s) of the ADC. Duringfunctional operation, the TEN signal controls the switch and multiplexerto couple the ADC to the functional analog input and the FCTL input(s).During test operation, the TEN signal controls the switch andmultiplexer to couple the ADC to the analog stimulus input and the TCTLinput(s).

FIG. 50 illustrates one example of how the TAP 804 may control theoperation of the control generator 904 of FIG. 48 . As seen the TAPcontrol bus 814 of FIG. 10 is expanded to include the TEN, RTI and TCKsignals described in FIG. 34 . To enable the control generator 904, theTAP is accessed via TAPI and TAPO to load an instruction into the TAPinstruction register 1002, which sets the TEN signal. Next, the TAP istransitioned into the Run Test/Idle state which sets the RTI signal.When TEN and RTI are both set, the control generator responds to the TCKinput to; (1) operate a stimulus control bus (SCB) 3302 to an analogwaveform generator 5002 in stimulus generator 902, (2) operate the TENand TCTL signals 3304 to ADC 4804 and (3) operate the response controlbus (RCB) 3306 to response collector 906. Response collector 906 may be,but is not limited to being, any of the described response collectorcircuits of FIGS. 37-40 .

When the SCB is operated, the analog waveform generator 5002 outputsanalog stimulus to ADC 4804. When the TEN and TCTL signals are operated,the ADC inputs the analog stimulus, converts it to digital response andoutputs the digital response. When the RCB is operated, the responsecollector inputs the digital response from the ADC.

FIG. 51 illustrates a first example implementation of an analog waveformgenerator 5002 of stimulus generator 902 for generating analog stimulusto ADC 4804. The waveform generator 5002 includes a digital to analogconverter (DAC) 5102 and a stimulus memory 1504, which may be a ROM or aRAM, as previously described. If it is a RAM memory a register 1506 willbe provided on the memory to allow the TAP to write data into the memoryvia control bus 814. The DAC has a data input bus coupled to thestimulus memory data output bus, control (CTL) input(s) from SCB 3302 ofcontrol generator 904 and an output for providing analog stimulus to theADC 4804. The stimulus memory 1504 has an address (ADD) input bus fromSCB 3302 of control generator 904 and data outputs to DAC 5102. When thecontrol generator 904 is enabled by TAP 804, it operates the memoryaddress bus to output data patterns to the DAC and operates the CTLinput(s) of the DAC to convert each of the data patterns into an analogstimulus output to the ADC 4804. These operations are repeated duringthe test.

FIG. 52 illustrates a second example implementation of an analogwaveform generator 5002 of stimulus generator 902 for generating analogstimulus to ADC 4804. The waveform generator 5002 includes a DAC 5102and a counter 5202. The DAC has a data input bus coupled to the counteroutput bus, CTL input(s) from SCB 3302 and an output for providinganalog stimulus to the ADC 4804. The counter has inputs for the TENsignal, a clock (CLK) signal and optionally an up/down (U/D) countcontrol signal from SCB 3302 and a count output bus to DAC 5102. Whenthe control generator 904 is enabled by TAP 804, it enables the counterfrom a known count state with the TEN signal and operates the counterwith the CLK signal. Each time a count pattern is output to the DAC thecontrol generator operates the CTL input(s) of the DAC to convert eachof the count patterns into an analog stimulus output to the ADC 4804. Ifused, the operational U/D signal from the control generator causes thecounter to count up and count down to create analog stimulus outputsthat controllably ramp up and ramp down.

FIG. 53 illustrates a third example implementation of an analog waveformgenerator 5002 of stimulus generator 902 for generating analog stimulusto ADC 4804. The waveform generator 5002 includes a DAC 5102 and apseudo-random pattern generator (PRPG) 5302. The DAC has a data inputbus coupled to the PRPG pattern output bus, CTL input(s) from SCB 3302and an output for providing analog stimulus to the ADC 4804. The PRPGhas inputs for the TEN and CLK signals from SCB 3302 and a patternoutput bus to DAC 5102. When the control generator 904 is enabled by TAP804, it enables the PRPG from a known pattern state with the TEN signaland operates the PRPG with the CLK signal. Each time a pattern is outputto the DAC the control generator operates the CTL input(s) of the DAC toconvert each of the patterns into an analog stimulus output to the ADC4804. This waveform generator 5002 produces pseudo-random amplitudeanalog stimulus outputs to ADC 4804.

FIG. 54 illustrates an example of a die 5402 coupled either directly orindirectly, through TSVs 803 of intermediate die 816, to the testinterposer 602 of FIG. 48 . The test interposer 602 is connected to theTAPI and TAPO signals of a TAP controller 2904. In this example, switch4806 is set to couple the outputs of stimulus generator 902 to theanalog stimulus inputs of a testable ADC 4804 in die 5402, multiplexer812 is set to couple the outputs of control generator 904 to the controlinputs of the testable ADC and the data response outputs from thetestable ADC are input to response collector 906. The stimulus generator902 may be, but is not limited to being, and of the stimulus generatorsof FIGS. 51-54 . The response collector 906 may be, but is not limitedto being, any of the previously describe response circuits 906.

As seen in FIG. 55 , the test begins by loading a test instruction intothe TAP 804 to set the TEN signal. After loading the instruction, theTAP is transitioned to the Run Test/Idle state to set the RTI signal toenable the control generator 904. While the TAP is in the RTI state, thecontrol generator 904 operates in at least a first state 5502, a secondstate 5504 and a third state 5506. In the first state 5502, the controlgenerator 904 operates stimulus generator 902 via the SCB 3302 togenerate an output analog stimulus to testable ADC 4804. In the secondstate 5504, the control generator operates the TEN and TCTL signals ofbus 3304 to operate the testable ADC to convert the analog stimulusinput into a digital response output. In the third state 5506, thecontrol generator 904 operates response collector 906 via RCB 3306 toinput the digital response from the testable ADC 4804. These states arerepeated during the test.

Testable DAC Example Using The Test Interposer

FIG. 56 illustrates a die 5602 containing a testable digital to analogconverter (DAC) 5604 coupled to a tester 1206 via a test interposer 602,either directly or indirectly via TSVs 803 of intermediate die 816. Thetest interposer includes a TAP 804, stimulus generator 902, controlgenerator 904, response collector 906 and multiplexers 810 and 812. Thecontrol generator can be controlled by the TAP via bus 814 to outputcontrol signals 3302 to stimulus generator 902, control signals 3304 tomultiplexer 812 and control signals 3306 to response collector 906.

If the test interposer 602 is set to allow the testable DAC 5604 to betested by the tester 1206, multiplexer 810 is controlled by TAP 804 toinput digital stimulus 824 to the DAC from tester 1206 via bus 118 andmultiplexer 812 is controlled by the TAP 804 to input test control 826to the DAC from tester 1206 via bus 118. The analog response from theDAC is output to tester 1206 via bus 120.

If the test interposer 602 is set to allow the testable DAC to be testedby the stimulus generator 902 and control generator 904, multiplexer 810and multiplexer 812 will be controlled by TAP 804 to couple the digitalstimulus output from the stimulus generator and the test control outputfrom the control generator to the DAC via buses 824 and 826. The analogresponse from the DAC is input to the response collector 906 via bus 825from bus 120.

FIG. 57 illustrates an example of a testable DAC 5604 that includes aDAC 5702, a digital input multiplexer 5704, and a control inputmultiplexer 5706. DAC 5702 has digital inputs, control (CTL) input(s),and an analog output. Multiplexer 5704 inputs functional digitalsignals, digital stimulus signals from bus 824, a TEN signal from bus826 and outputs digital signals to the digital inputs of the DAC.Multiplexer 5706 inputs functional control (FCTL), test control (TCTL)from bus 826, the TEN signal and outputs control to the CTL input(s) ofthe DAC. During functional operation, the TEN signal controls themultiplexers to couple the DAC to the functional digital inputs and theFCTL input(s). During test operation, the TEN signal controls themultiplexers to couple the DAC to the digital stimulus inputs and theTCTL input(s).

FIG. 58 illustrates one example of how the TAP 804 may control theoperation of the control generator 904 of FIG. 56 . As seen the TAPcontrol bus 814 of FIG. 10 is expanded to include the TEN, RTI and TCKsignals described in FIG. 34 . To enable the control generator 904, theTAP is accessed via TAPI and TAPO to load an instruction into the TAPinstruction register 1002, which sets the TEN signal. Next, the TAP istransitioned into the Run Test/Idle state which sets the RTI signal.When TEN and RTI are both set, the control generator responds to the TCKinput to; (1) operate a stimulus control bus (SCB) 3302 to the stimulusgenerator 902, (2) operate the TEN and TCTL signals 3304 to DAC 5604 and(3) operate the response control bus (RCB) 3306 to an analog responsecircuit 5802 in response collector 906. Stimulus generator 902 may be,but is not limited to being, any of the described stimulus generatorcircuits of FIGS. 35 and 36 .

When the SCB is operated, the stimulus generator 902 outputs digitalstimulus to DAC 5604. When the TEN and TCTL signals are operated, theDAC inputs the digital stimulus, converts it to an analog responsesignal and outputs the analog response signal. When the RCB is operated,the analog response circuit 5802 in response collector 906 inputs theanalog response signal from the DAC.

FIG. 59 illustrates an example implementation of an analog responsecircuit 5802 of response collector 906 for inputting the analog responseoutput from DAC 5604. The analog response circuit 5802 includes ananalog to digital convertor (ADC) 5902 and a response memory 2104, whichmay be a RAM. A register is provided on the memory 2104 to allow the TAPto read data from the memory via control bus 814. The ADC has a digitaloutput bus coupled to the response memory data input bus, control (CTL)input(s) from SCB 3302 of control generator 904 and an analog inputcoupled to the analog response output of the DAC 5604. The responsememory 2104 has an address (ADD) input and a write (WR) input from SCB3302 of control generator 904 and data inputs coupled to ADC 5902. Whenthe control generator 904 is enabled by TAP 804, it operates the CTLinput(s) to the ADC to convert an analog response signal from DAC 5604into a digital representation, operates the ADD inputs to the responsememory to select a memory location and operates the WR input to theresponse memory to write the digital representation into the memorylocation. These operations are repeated during the test.

FIG. 60 illustrates an example of a die 5602 coupled either directly orindirectly, through TSVs 803 of intermediate die 816, to the testinterposer 602 of FIG. 56 . The test interposer 602 is connected to theTAPI and TAPO signals of a TAP controller 2904. In this example,multiplexer 810 is set to couple the outputs of stimulus generator 902to the digital stimulus inputs of a testable DAC 5604 in die 5602,multiplexer 812 is set to couple the outputs of control generator 904 tothe control inputs of the testable DAC and the analog response outputsfrom the testable DAC are input to response collector 906. The stimulusgenerator 902 may be, but is not limited to being, any of the stimulusgenerators of FIGS. 35-36 . The response collector 906 may be, but isnot limited to being, the response collector of FIG. 59 .

As seen in FIG. 61 , the test begins by loading a test instruction intothe TAP 804 to set the TEN signal. After loading the instruction, theTAP is transitioned to the Run Test/Idle state to set the RTI signal toenable the control generator 904. While the TAP is in the RTI state, thecontrol generator 904 operates in at least a first state 6102, a secondstate 6104 and a third state 6106. In the first state 6102, the controlgenerator 904 operates stimulus generator 902 via the SCB 3302 togenerate and output digital stimulus to testable DAC 5604. In the secondstate 6104, the control generator operates the TEN and TCTL signals ofbus 3304 to operate the DAC to convert the digital stimulus inputs intoan analog response output. In the third state 6106, the controlgenerator 904 operates response collector 906 via RCB 3306 to input theanalog response from the DAC 5604. These states are repeated during thetest.

FIG. 62 illustrates a first example of a die 6202 with analog or digitaltest circuitry 6204 mounted on top of a die 6206 with analog or digitaltest circuitry 6208 which is mounted on a test interposer 602 of thedisclosure.

The stimulus bus (SB) to test circuitry 6204 comes from one of a TAPcontrolled multiplexer and analog switch (M/S) 6210 via TSVs 803 of die6206. M/S 6210 receives stimulus input from either a tester via a SB onbus 118 or a TAP controlled stimulus generator (SG) 6212. The stimulusbus (SB) to test circuitry 6208 comes from one of a TAP controlled M/S6214. M/S 6214 receives stimulus input from either a tester via a SB onbus 118 or a TAP controlled SG 6216. SGs 6212 and 6216 may be, but arenot limited to being, any of the previously described SGs 902.

The control bus (CB) to test circuitry 6204 comes from a TAP controlledmultiplexer (M) 6218 via TSVs 803 of die 6206. M 6218 receives controlinput from either a tester via a CB on bus 118 or a TAP controlledcontrol generator (CG) 6220. The CB to test circuitry 6208 comes from aTAP controlled M 6222. M 6222 receives stimulus input from either atester via a CB on bus 118 or a TAP controlled CG 6224. CGs 6220 and6224 may be, but are not limited to being, any of the previouslydescribed CGs 904.

The response bus (RB) from test circuitry 6204 is output to a TAPcontrolled response collector (RC) 6228 and to a tester via a RB on bus120. The RB output from test circuitry 6208 passes through TSVs 803 ofdie 6206. The RB from test circuitry 6208 is output to a TAP controlledRC 6226 and to a tester via a RB on bus 120. RCs 6226 and 6228 may be,but are not limited to being, any of the previously described RCs 906.

While not shown, CG 6220 provides control input 3302 to SG 6212 andcontrol input 3306 to RC 6228 and CG 6224 provides control input 3302 toSG 6216 and control input 3306 to RC 6226, as shown in FIG. 43 .

FIG. 63 illustrates a second example of a die 6302 with analog ordigital test circuitry 6304 mounted on top of a die 6306 with analog ordigital test circuitry 6308 which is mounted on a test interposer 602 ofthe disclosure. Instead of using separate SB, CB and RB interfaces toeach test circuit 6304 and 6308 of FIG. 63 , this example uses a commonstimulus bus (CSB), a common control bus (CCB) and a common response bus(CRB) interface to test circuits 6304 and 6308.

As seen, an n-wide CSB is input to test circuits 6304 and 6308 from oneof a TAP controlled multiplexer and analog switch (M/S) 6310. The CSB totest circuit 6304 passes through TSVs 803 of die 6306. M/S 6310 receivesstimulus input from either a tester via the CSB on bus 118 or a TAPcontrolled programmable stimulus generator (PSG) 6312.

An m-wide CCB is input to test circuits 6304 and 6306 from a TAPcontrolled multiplexer (M) 6314. The CCB to test circuit 6304 passesthrough TSVs 803 of die 6306. M 6314 receives control input from eithera tester via the CCB on bus 118 or a TAP controlled programmable controlgenerator (PCG) 6316.

The response output from test circuits 6304 and 6308 are selectivelycoupled to an n-wide common response bus (CRB) via tri-state buffers oranalog switches 6320 and 6322 associated with the test circuits. Whentest circuit 6304 is being operated, a TEN signal from the CCB willenable buffer/switch 6320 and when test circuit 6308 is being operated,a TEN signal from the CCB will enable buffer/switch 6322. When testcircuit 6304 is being accessed, its response output will pass throughTSVs 803 of die 6306. The CRB is input to a TAP controlled programmableresponse collector (PRC) 6318 and is output to a tester on bus 120.

The number of stimulus inputs to test circuits 6304 and 6308 may be lessthan or equal to the n-wide CSB, the number of control inputs to testcircuits 6304 and 6308 may be less than or equal to m-wide CCB and thenumber of response outputs from test circuit 6304 and 6308 may be lessthan or equal to the n-wide CRB. In this example it is assumed that oneof the test circuits requires an n-wide CSB, an m-wide CCB and an n-wideCRB and the other test circuit may require a lesser-wide CSB, CCB andCRD.

FIG. 64 illustrates one example implementation of the programmablestimulus generator (PSG) 6312 of FIG. 63 . The PSG includes a number ofstimulus generators 902 connected to TAP 804 via bus 814. The outputs ofthe stimulus generators 902 are selectively coupled to the CSB via astimulus multiplexer and/or analog switch 6402 by a select (SEL) signal6404 from TAP control bus 814. Once coupled, a stimulus generator 902may be enabled by the TAP to output analog or digital stimulus to atarget test circuit of a die. The stimulus generators 902 may be, butare not limited to being, any of the previously described examplestimulus generators 902.

FIG. 65 illustrates one example implementation of the programmablecontrol generator (PCG) 6316 of FIG. 63 . The PCG includes a number ofcontrol generators 904 connected to TAP 804 via bus 814. The outputs ofthe control generators 904 are selectively coupled to the CCB via acontrol multiplexer 6502 by a select (SEL) signal 6504 from TAP controlbus 814. Once coupled, a control generator 904 may be enabled by the TAPto output control to a target test circuit of a die. The controlgenerators 904 may be, but are not limited to being, any of thepreviously described example control generators 904.

FIG. 66 illustrates one example implementation of the programmableresponse collector (PRC) 6318 of FIG. 63 . The PRC includes a number ofresponse collectors 906 connected to the CRB and to TAP 804 via bus 814.When enabled by the TAP a response collector inputs the response datafrom a selected test circuit via the CRB. The response collectors 906may be, but are not limited to being, any of the previously describedexample response collectors 906.

Both the test interposer and die stack example of FIGS. 62 and 63 areanticipated in this disclosure. The advantage of the FIG. 62 example isthat multiple die test circuits may be tested simultaneously sinceseparate stimulus, control and response buses are provided. Theadvantage of the FIG. 63 example is the use of common stimulus, controland response buses to each die which reduces the number of testconnections between the test interposer and the bottom die and betweendie stacked on top of the bottom die. Furthermore, the use of commonstimulus, control and response buses reduces the number of test TSVs 803that must be included in each die in the stack.

While this disclosure has described the test interposer as being animprovement to a conventional silicon interposer die 106 which functionsas a signal redistribution layer between a stack of die and a substrateon to which it will be mounted, this disclosure anticipates the signalredistribution function of the interposer being incorporated within thebottom die of a stack of die. This will in effect remove one layer inthe stack, the interposer, from being required as a separate entity in astacked die arrangement. Therefore, the test circuitry of the testinterposer described herein should be understood to be likewiseincorporated within the bottom die of a stack of die. Thus the bottomdie of a stack may, according the present invention, include; (1)functional/test circuitry, (2) signal redistribution connections and (3)the test circuitry described in this disclosure.

FIG. 67 illustrates an arrangement 6700 which incorporates, as describedabove, the test interposer 602 of this disclosure into a bottom die 6706onto which one or more die 6702 may be stacked. Each die in the stackincludes both functional circuitry 402 and test circuitry 404 as shownin FIG. 4 . The test circuitry may be analog or digital test circuitry.The functional and test circuitry of each die are connected to inputsand outputs of the die. The bottom die 6706 may be connected to asubstrate or tester 6710. The test interposer 602 of die 6706 includesat least some or all of the test circuits described in this disclosure,such as a TAP, a stimulus generator, a control generator, a responsecollector, a multiplexer and an analog switch. During functionaloperation, the test interposer operates as a conventional interposer topass functional input and output signals to and from functionalcircuitry of each die in the stack. During test operation, the testinterposer operates, as described in this disclosure, to pass test inputand output signals to and from test circuitry of each die in the stack.Thus testing, using the test interposer of this disclosure, may beachieved by realizing the test interposer as a separate entity ontowhich a die stack is mounted or by realizing the test interposer as anembedded circuit within the bottom die of a die stack.

Although the disclosure has been described in detail, it should beunderstood that various changes, substitutions and alterations may bemade without departing from the spirit and scope of the disclosure asdefined by the appended claims.

1. An interposer comprising: a first face; a second face; test accessport circuitry including a test data input coupled to the first face, atest clock input coupled to the first face, a test mode select inputcoupled to the first face, a test data output coupled to the first face,and control output; stimulus generator circuitry including a first inputcoupled to the control output of the test access port circuitry, whereinthe stimulus generator circuitry further includes a stimulus output; afirst multiplexer including a first data input coupled to the firstface, a second data input coupled to the stimulus output, a controlinput coupled to the control output of the test access port circuitry,and an output coupled to the second face.
 2. The interposer of claim 1,further comprising response collector circuitry including: a controlinput coupled to the control output of the test access port circuitry;and a data input coupled to the second face.
 3. The interposer of claim2, further comprising a bus coupled to the first face, coupled to thedata input of the response collector circuitry, and coupled to thesecond face.
 4. The interposer of claim 1, further comprising controlgenerator circuitry including: an input coupled to the control output ofthe test access port circuitry; and an output coupled to the stimulusgenerator circuitry.
 5. The interposer of claim 4, further comprising asecond multiplexer including: a data input coupled to the controlgenerator circuitry; a control input coupled to the control output ofthe test access port circuitry; and an output coupled to the secondface.
 6. The interposer of claim 4, further comprising responsecollector circuitry including: a first input coupled to the controlgenerator circuitry; a second input coupled to control output of thetest access port circuitry; and a data output coupled to the secondface.
 7. The interposer of claim 1, further comprising a bus coupled tothe first face, coupled to the first data input of the firstmultiplexer, and coupled to the second face.
 8. The interposer of claim7, further comprising a second multiplexer including: a first data inputcoupled to the bus; a second data input coupled to the control output ofthe test access port circuitry; and an output coupled to the secondface.
 9. The interposer of claim 1, further comprising a secondmultiplexer including: a data input coupled to the control output of thetest access port circuitry; a control input coupled to the controloutput of the test access port circuitry; and an output coupled to thesecond face.
 10. The interposer of claim 1, wherein the first face isconfigured to couple to a tester, and wherein the second face isconfigured to couple to a semiconductor die.
 11. A method comprising:receiving, by a test access port circuit in an interposer, aninstruction to perform a test; enabling, by the test access port circuitin response to receiving the instruction, other circuitry in theinterposer to the perform the test; entering, by the test access portcircuit, a run-test idle state after enabling the other circuitry;outputting, by the test access port circuit, results of the test. 12.The method of claim 11, further comprising remaining, by the test accessport circuit, in the run-test idle state while the other circuitryperforms the test.
 13. The method of claim 11, further comprisingexiting, by the test access port circuit, the run-test idle state afterthe other circuitry completes the test.
 14. The method of claim 11,wherein enabling the other circuitry comprises enabling the othercircuitry to perform a digital test in a semiconductor die coupled tothe interposer.
 15. The method of claim 11, wherein enabling the othercircuitry comprises enabling the other circuitry to perform an analogtest in a semiconductor die coupled to the interposer.
 16. An interposercomprising: a first face; a second face; test access port circuitryincluding a test data input coupled to the first face, a test clockinput coupled to the first face, a test mode select input coupled to thefirst face, a test data output coupled to the first face, and controloutput; control generator circuitry including a first output, a secondoutput, a third output, and an input coupled to the control output ofthe test access port circuitry; stimulus generator circuitry including afirst input coupled to the control output of the test access portcircuitry, a second input coupled to the first output of the controlgenerator circuitry, and a stimulus output; response collector circuitryincluding a first input coupled to the control output of the test accessport circuitry, a second input coupled to the second output of thecontrol generator circuitry, and a third input coupled to the secondface; a first multiplexer including a first data input coupled to thefirst face, a second data input coupled to the stimulus output, acontrol input coupled to the control output of the test access portcircuitry, and an output coupled to the second face; and a secondmultiplexer including a first data input coupled to the first face, asecond data input coupled to the third output of the control generatorcircuitry, a control input coupled to the control output of the testaccess port circuitry, and an output coupled to the second face.
 17. Theinterposer of claim 16, further comprising: a first bus coupled thefirst face; and a second bus coupled the first face and the second face,wherein the first data input of the first multiplexer is coupled to thefirst bus, wherein the first data input of the second multiplexer iscoupled to the first bus, and wherein the third input of the responsecollector circuitry is coupled to the second bus.
 18. The interposer ofclaim 17, wherein the first bus is coupled to the second face.